The invention relates to a braced parallelogram linkage for moving members together or apart in a substantially linear motion without a substantial shift in a direction perpendicular to the desired linear motion. Typical parallelogram linkages that are commonly used for a variety of purposes involve a pair of parallel members attached pivotally to a pair of parallel linkage members. If one of the parallel members is fixed, then motion of the parallelogram linkage results in an angular motionxe2x80x94in or out and up or down rather than simply in or out. The present invention relates to a generally straight motion parallelogram linkage.
The invention disclosed herein is particularly useful as a control mechanism for expandable rooms in habitable structures, especially room structures that are telescopically slideable between retracted and extended positions for motorized or towed vehicles. A variety of vehicles are known and used that have a room or a room portion that may be moved from a retracted position while the vehicle is moving over the road to an extended position when the vehicle is stationary in order to provide additional internal space. This type of an arrangement provides adequate space to accommodate users when a recreational vehicle is parked for habitation while still keeping the vehicle within governmental regulations that impose width limitations for vehicles on roads and highways. When these vehicles are stationary, they are frequently used for habitation for extended periods of time, and when so used, it is highly desirable to be able to maximize the available living space. This is done in a variety of ways in which the user can move a xe2x80x9cnestedxe2x80x9d portion of the expandable room out to its extended or expanded position, typically under hydraulic or electrical power.
These expandable room portions usually comprise a structure that includes a floor, a roof, an external side wall (typically generally parallel to the vehicle side wall), an open (or openable), interior side wall, and one or more end walls (typically generally perpendicular to the vehicle side wall). These components are typically made of frame members and wall panels. In the retracted position, the roof, floor and end walls are typically concealed from exterior view and the room exterior side wall forms a portion of the vehicle side wall. A large factor in the purchase of a vehicle of this type is the amount of space that is available inside the vehicle. Thus, it is desirable that the mechanism for extending and retracting the room occupy a minimum amount of space within the vehicle.
The prior art for expanding and retracting expandable rooms generally employs hydraulic arms that are housed inside the vehicle or under the floor of the vehicle. The hydraulic arms housed inside the vehicle require a housing unit when they are in their retracted position. This housing unit remains intact when the room is extended taking up space within the vehicle.
The hydraulic arms that are housed under the floor are generally complex, relatively expensive, and may be unduly heavy. The additional weight also adversely affects the fuel economy of the vehicle. With the highly competitive market in these recreational vehicles, cost and reliability of operation are important factors. Further, when the room is in the retracted position, otherwise available storage space under the floor is lost.
It is therefore an object of the invention to provide an improved mechanism for expandable rooms for vehicles that is relatively inexpensive to manufacture, reliable in use, lightweight, and which will allow for maximum space inside the vehicle. It is a further object to provide a braced parallelogram linkage that permits motion of members together or away from one another in a substantially linear path without substantial movement of said members in a direction perpendicular to said path. It is a further object to provide a mechanism for the expansion and retraction of expandable rooms or structures when the rooms or structures are not disposed for convenient housing of the mechanism in the floor. Finally, it is an object of the present invention to provide such a parallelogram linkage mechanism wherein a force assist means such as, for example, a hydraulic cylinder, electric drive, or pneumatic control system may drive the movement of the braced parallelogram linkage.
The present invention includes an extension assembly for manual operation or having a hydraulic cylinder or other force assist such as a pneumatic control system, electric drive or other similar system, mounted to effect the coordinated movement of braced parallelogram linkage members through the actuation of a glide arm or rolling support arm. The glide arm or rolling support arm preferably moves generally along a first structural member such as a vehicle frame member as the hydraulic cylinder rod extends or retracts relative to the cylinder body or as manual operation moves structural members relative to one another. The glide arm is pivotally connected to the exterior ends of braced parallelogram linkage members that extend to points of pivotal attachment with a second structural member, such as expandable room members. The glide arm has an opening formed therein to accommodate movement of the glide arm about a bracing member that is pivotally attached to the first structural member such as vehicle frame member.
The braced parallelogram linkage members comprise a first parallel linkage member that is braced by a first parallel linkage bracing member, and a second parallel linkage member that is braced by a second parallel linkage bracing member. The parallel linkage bracing members are pivotally attached to the respective parallel linkage members and they are also attached to the first structural member. In this manner, movement of the glide arm or rolling support arm causes the exterior ends of the parallel linkage members to move and pivot thus extending or retracting the room and changing the relative angles between the parallel linkage members and the parallel linkage bracing members, the parallel linkage members and the first structural member, and the parallel linkage members and the second structural member, respectively.